1. Technical Field of the Invention
The present invention regards a spacer device for the two-stage treatment of arthroprosthesis infections, for example hip prostheses, humeral prostheses, knee prostheses, ankle prostheses, etcetera.
2. Description of Related Art
Arthroprosthesis infections are among the most serious causes of failure of an arthroprosthesis. With specific reference to hip arthroprostheses, such events occur quite often with a percentage variable between 0.5% and 6% of the cases. The percentage of negative events increases in cases of re-implantation or in presence of risk factors such as previous interventions, local haematoma, intercurrent infectious diseases, local or general bone diseases, immunosuppression, etcetera.
A method for curing the infection, defined a two-stage treatment, provides for a first stage of removing the infected arthroprosthesis, the possibilities of success of the conservative antibiotic treatment are actually quite limited, and a second stage of a new re-implant of arthroprosthesis upon clearing the tissues of the patient in terms of infection.
In order to maintain the space required for the new re-implantation of arthroprosthesis and cure the infection, the applicant developed special arthroprostheses for temporary use, also referred to as spacers or temporary spacers, which release pharmaceutical and/or therapeutic products and allow articular mobility.
The aforementioned spacers are disclosed by the Italian patent No. IT-1278853 and European patent No. EP-1274374 on behalf of the applicant, the contents of which are incorporated herein by reference.
The International patent application WO-2007/099232 discloses a temporary spacer comprising a semispherical head to be inserted in the corresponding articulation separable and connectable to a stem to be inserted in the bone bed remaining from a previous implant. The spacer illustrated in WO-2007/099232 allows combining a stem with semispherical heads of different sizes so as to best adapt to the anatomy of the articulation of the patient.
There arises the need of providing a solution alternative to the known ones, in particular more efficient, safe and inexpensive as regards the mutual locking between the stem and the head.